Three-position selector valve

ABSTRACT

A selector valve ( 102 ) having at least first and second ports ( 108  and  110 ) is provided. The selector valve includes a closure element ( 120 ) selectively displaceable between a first position, wherein the closure element ( 120 ) sealingly engages the first port ( 108 ), and a second position, wherein the closure element ( 120 ) sealingly engages the second port ( 110 ). The selector valve ( 102 ) further includes a cam assembly that is configured to bias the closure element ( 120 ) into at least the first or second position in a manner such that the closure element ( 120 ) does not come into substantial contact with the first or second port ( 108  or  110 ) when being moved into the first or second position.

BACKGROUND

Valves are commonly used to control fluid passing through a pipe or afluid system. To effectively regulate the flow of the fluid, the valvemust be able to contain the fluid without external leakage, it must beable to withstand the pressure of the fluid, and the plug or closureelement should be able to withstand wear and distortion over time.

Fluid systems use many different types of valve assemblies. Selectorvalves are used to direct flow coming from or going to multiple sources.For instance, Class 8 vehicles often include a fuel storage arrangementthat utilizes multiple fuel tanks. Such an arrangement requires the useof a fuel selector valve assembly to draw fuel from one or two tanks andreturn fuel to the tanks. Although current fuel selector valveassemblies are effective, they are not without their problems. Many fuelselector valve assemblies fail to sufficiently control the flow of fuelbetween the fuel selector valve and the fuel tanks, thereby leading toinefficiencies. As a non-limiting example, many fuel selector valveassemblies allow unwanted siphoning due to vehicle attitude. Moreover,the design of the fuel selector valve often causes valve components towear over time, leading to leakage and failure.

The present application depicts at least one embodiment of a low cost,reliable, efficient selector valve that may be used with any suitableselector valve assembly.

SUMMARY

A selector valve having at least first and second ports is provided. Theselector valve includes a closure element selectively displaceablebetween a first position, wherein the closure element sealingly engagesthe first port, and a second position, wherein the closure elementsealingly engages the second port. The selector valve further includes acam assembly that is configured to bias the closure element into atleast the first or second position in a manner such that the closureelement does not come into substantial contact with the first or secondport when being moved into the first or second position.

This summary is provided to introduce a selection of concepts in asimplified form that are further described below in the DetailedDescription. This summary is not intended to identify key features ofthe claimed subject matter, nor is it intended to be used as an aid indetermining the scope of the claimed subject matter.

DESCRIPTION OF THE DRAWINGS

The foregoing aspects and many of the attendant advantages of thepresent disclosure will become understood by reference to the followingdetailed description, when taken in conjunction with the accompanyingdrawings, wherein:

FIG. 1 is an environmental view of first and second selector valvesembodied in a representative fuel selector valve assembly constructed inaccordance with one embodiment of the present disclosure;

FIG. 2 is an exploded view of the fuel selector valve assembly of FIG.1;

FIG. 3 is a front planar view of the fuel selector valve assembly ofFIG. 1;

FIG. 4 is a sectional view of the fuel selector valve assembly of FIG.3, taken substantially through Section 4-4 of FIG. 3;

FIG. 5 is an exploded view of a first housing receptacle for the fuelselector valve assembly of FIG. 1, showing a drive gear, a drive axle,and a motor;

FIG. 6 is a cross sectional view of the fuel selector valve assembly ofFIG. 1 depicting the first and second selector valves, takensubstantially through Section 6-6;

FIG. 7 is a partial cross-sectional view of the first selector valve ofthe fuel selector valve assembly of FIG. 1, taken substantially throughSection 7-7 of FIG. 3; and

FIG. 8 is a partial cross-sectional view of the first selector valve ofthe fuel selector valve assembly of FIG. 1, taken substantially throughSection 8-8 of FIG. 3.

DETAILED DESCRIPTION

The present disclosure depicts a selector valve for selectively placingat least one external source of fluid, air, etc. in communication withone or more other external sources. As a non-limiting example and forease of illustration and description only, a selector valve constructedin accordance with one embodiment of the present disclosure is shown inFIGS. 1-8 embodied within a representative fuel selector valve assembly100. The fuel selector valve assembly includes a first selector valve,or fuel draw valve 102, a second selector valve, or fuel return valve104, and a drive system 106 disposed therebetween.

Although the first and second selector valves are shown embodied withina fuel selector valve assembly 100, it should be appreciated that thedisclosed first and/or second selector valves may instead be used inmany other valve assemblies and systems. Thus, it should be appreciatedthat the description of the selector valve in a fuel selector valveassembly 100 is for illustrative purposes only, and should not beconstrued as limiting the claimed subject matter.

The fuel draw valve 102 of the fuel selector valve assembly 100 includesfirst and second fuel tank draw ports 108 and 110 and an engine drawport 112. The first and second fuel tank draw ports 108 and 110 areadapted to be placed into fluid communication in any well-known mannerwith first and second fuel tanks (not shown) of a vehicle. It should beappreciated that the first and second fuel tank draw ports 108 and 110may instead be placed in fluid communication with multiple fuel tanks.The engine draw port 112 is adapted to be placed into fluidcommunication with an engine.

The fuel return valve 104 includes first and second fuel tank returnports 114 and 116 and an engine return port 118, wherein the first andsecond fuel tank return ports 114 and 116 are adapted to be placed influid communication with the first and second fuel tanks, and the enginereturn port 118 is adapted to be placed into fluid communication withthe engine. Similar to the first and second fuel tank draw ports 108 and110, the first and second fuel tank return ports 114 and 116 may insteadbe placed in fluid communication with multiple fuel tanks.

As may best be seen by referring to FIGS. 1 and 4, the fuel selectorvalve assembly 100 includes a drive system 106 having a gear motorhousing 124 formed by coupling first and second housing halves 126 and128 together in any well-known manner. Disposed within the motor housing124 is a gear assembly 130 and motor 132.

The motor 132 is any well-known electrical motor, such as a conventionalbrush or brushless motor with an output shaft 138. The motor 132 mayinclude a contact (not shown) for connecting the motor 132 to anexternal power source and control system, thus allowing for selectiveactuation of the motor 132. The output shaft 138 of the motor 132includes a worm gear 154 fixedly coupled in a coaxial manner thereto.

Still referring to FIG. 4, the worm gear 154 is mechanically coupled toa first spur gear 156, which is journaled for rotation on a first gearaxle 158. A second spur gear 160 is also journaled for rotation on thefirst gear axle 158. A third spur gear 162 is journaled for rotation ona second gear axle 164 and is mechanically coupled to the second spurgear 160 for rotation therewith. A fourth spur gear 166 is journaled forrotation on the second gear axle 164 and is mechanically coupled to adrive gear 168 journaled for rotation within the housing on a drive axle172.

Referring to FIGS. 2 and 6, the drive axle 172 is suitably a rod-shapedmember having one end shaped and configured to mechanically connect in akeyed manner or any other suitable manner to the fuel draw valve 102.The other end of the drive axle 172 is shaped and configured tomechanically connect to the fuel return valve 104. If mechanicallyconnecting the fuel return valve 104 is not required, however, thesecond end of the drive axle 172 may be truncated.

Still referring to FIGS. 2 and 6, first and second closure elements arereceived on opposite ends of the drive axle 172. Preferably, the firstand second closure elements consist of first and second ball valves 120and 122. As can best be seen by referring to FIGS. 7 and 8, each ballvalve 120 and 122 includes a stem 302, a coil spring 306 disposed on thestem 302, a rounded ball cap 304 coupled to the end of the stem 302, andtwo opposing ball posts 292 extending outwardly and laterally from theball cap 304. The first and second ball valves 120 and 122 are receivedon the ends of the drive axle 172 in a manner well-known in the art suchthat the drive axle 172 passes through the stem 302 and the ball cap 304extends outwardly therefrom. The coil spring 306 is disposed betweeneach ball cap 304 and the drive axle 172 such that the ball valves 120and 122 are spring-loaded outwardly from the drive axle 172. The ballvalves 120 and 122 may instead be attached to the drive axle 172 in anysuitable manner such that the ball valves 120 and 122 are continuouslybiased in a direction opposite the drive axle 172. Although a ball valveis suitable for use as a closure element, other types of valves orclosure elements are also within the scope of the present disclosure.

Referring to FIGS. 2 and 6, the motor housing 124 includes first andsecond gear/motor interface portions 274 and 276 formed on the exteriorof the first and second housing halves 126 and 128 for interfacing thefuel draw valve 102 and the fuel return valve 104, respectively. Eachgear/motor interface portions 274 and 276 defines a first cam 287 havinga first cam surface 288. The first cam 287 is part of a cam assembly,which also includes a second cam 285. The first cam 287 is substantiallyidentical in shape and size to the second cam 285 formed within the fueldraw valve 102, which is described in greater detail below with respectto FIG. 7. Therefore, a detailed description of the first cam 287 willbe omitted. Each of the first and second gear/motor interface portions274 and 276 includes at least one O-ring 294 (only one O-ring 294 isillustrated in FIG. 2 for clarity). The O-ring 294 is received around aportion of gear/motor interface portion and provides a seal when thegear/motor interface portion 274 or 276 engages the cam-receivingportion 220 of the fuel draw valve 102 or fuel return valve 104,respectively, as described in greater detail below.

As may best be seen by referring to FIG. 4, the selector valve 100further includes a printed circuit board 176 mounted within the secondhousing receptacle 128. The printed circuit board 176 includes aplurality of sensors or switches 178, wherein each switch 178 engagesone of the protrusions 188 (see also FIG. 5) formed on one surface ofthe drive gear 168 when the drive gear 168 rotates. The printed circuitboard 176 is electrically coupled at one end to pins 187 of anelectrical connector 186, as shown in FIG. 2, for placing the circuitboard 176 in electrical communication with an external control system(not shown). A protrusion 188 engages a switch 178 when the drive gear168 is rotated to displace the fuel draw valve 102 into one of thepositions, thereby tripping the switch 178 and sending a signal to themotor 132 to turn off.

The structure of the fuel draw valve 102 may best be understood byreferring to FIGS. 1 and 7. The fuel return valve 104 is substantiallyidentical in size and shape; therefore, only the fuel draw valve 102will be described. The fuel draw valve 102 includes a hollow cylindricalvalve body 204 with two open ends that define the first fuel tank drawport 108 and the second fuel tank draw port 110. A first hollowcylindrical member 210 intersects the hollow cylindrical valve body 204in substantially the center of the valve body 204 to form the enginedraw port 112. The interior of the first hollow cylindrical member 210is in fluid communication with the interior of the hollow cylindricalvalve body 204.

A second, hollow, open-ended cylindrical member 214 intersects thehollow cylindrical valve body 204 in substantially the center of thevalve body 204 to form a cam-receiving portion 220 (see the fuel returnvalve 104 in FIG. 2). The interior of the second hollow cylindricalmember 214 is in fluid communication with the interior of the hollowcylindrical valve body 204.

Referring to FIGS. 7 and 8, the intersection of the first hollowcylindrical member 210, second hollow cylindrical member 214, and hollowcylindrical valve body 204 defines a ball valve receptacle 222. Theinterior closed end of the second hollow cylindrical member 214 includesa second cam 285 that defines a second cam surface 289. Disposed withinthe middle of the cam 285 is an annular projection that defines acylindrical receptacle 316.

The second cam 285 is substantially oval in shape having arcuate upperand lower cam surfaces 296 and 297. As the upper cam surface 296 extendstowards the first fuel tank draw port 108, the upper cam surface 296gradually extends inwardly towards the middle of the cam 285 toeventually define a first lip 278 near the intersection of the upper andlower cam surfaces 296 and 297. The first lip 278 defines a first pocket290 adjacent thereto between the upper and lower cam surfaces 296 and297.

As the lower cam surface 297 extends towards the second fuel tank drawport 110, the lower cam surface 297 gradually extends inwardly towardsthe middle of the cam 285 to eventually define a second lip 280 near theintersection of the upper and lower cam surfaces 296 and 297. The secondlip 280 defines a second pocket 291 adjacent thereto between the upperand lower cam surfaces 296 and 297.

Still referring to FIGS. 7 and 8, an annular seal 236 is received withinthe first and second fuel tank draw ports 108 and 110. The contour ofthe annular seal 236 substantially conforms to the shape of the insidesurface of the fuel tank draw ports 108 and 110 such that the annularseal 236 is sealingly received therewithin. A hollow connector plug 242is also received within the first and second fuel tank draw ports 108,110 such that the connector plug 242 abuts the annular seal 236. Theconnector plug 242 substantially conforms to the size of the interiorsurface of the first and second fuel tank draw ports 108 and 110 to forma friction fit therebetween.

The connector plug 242 is suitably shaped to receive a standard valvefitting (not shown) therewithin, such as any number of commonly knownfitting systems. A valve fitting is similarly received within the enginedraw port 112. Any suitable fuel line or tube (not shown) may be coupledto the valve fittings to either draw fuel into the fuel draw valve 102or carry fuel out of the fuel draw valve 102.

As shown in FIGS. 1 and 3, the fuel draw valve 102, the drive system106, and the fuel return valve 104 are coupled together to cooperativelyform a selector valve assembly 100. However, it can be appreciated thatonly the fuel draw valve 102 and the drive system 106 may be coupledtogether if the fuel return valve 104 is not needed.

As can best be seen by referring to FIGS. 2 and 6, the fuel draw valve102 is coupled to the drive system 106 by mating the cam-receivingportion 220 with the first gear/motor interface portion 274 of the firsthousing receptacle 126. At least one O-Ring 294 or other seal may bereceived therebetween to sealingly engage the first gear/motor interfaceportion 274 with the cam-receiving portion 220. A plurality of fastenerssuch as screws, bolts, etc. pass through reciprocal openings formed inthe fuel draw valve 102 and the first housing receptacle 126 to securelycouple the fuel draw valve 102 to the drive system 106. Other methods offastening, such as glue, rivets, etc. may also be appreciated.

The drive axle 172, which protrudes out of the first gear/motorinterface portion 274, receives a first ball valve 120 and is thereafterreceived into the ball valve receptacle 222 of the fuel draw valve 102.The end of the drive axle 172 includes an axle post 312 that isrotatably received within the cylindrical receptacle 316 such that thefirst ball valve 120 is rotatably received within the ball valvereceptacle 222.

The fuel return valve 104 is coupled to the drive system 106 in asubstantially identical manner, except that a mounting bracket 318 ispreferably disposed between the second housing receptacle 128 of thedrive system 106 and the fuel return valve 104. The mounting bracket 318is preferably L-shaped in cross-section, and it includes a circularopening that receives the second gear/motor interface portion 276. Themounting bracket 318 may be used for mounting the three-positionselector valve 100 within a vehicle (not shown).

Operation of the selector valve assembly 100 may best be understood byreferring to FIG. 4. The drive system 106 is activated to selectivelyplace the selector valve assembly 100 in communication with the fueltanks and the engine. The motor 132 rotates the output shaft 138, whichin turn drives the worm gear 154. As such, the worm gear 154 providesrotational force to the first spur gear 156, thereby causing the firstspur gear 156 to rotate in a preselected direction from its initialposition. The rotation of the first spur gear 156 in turn causes thesecond spur gear 160 to simultaneously rotate. The rotation of thesecond spur gear 160 provides rotational force to drive the third spurgear 162, thereby causing the third spur gear 162 to rotate in apreselected direction from its initial position. When the third spurgear 162 is driven by the second spur gear 160, the fourth spur gear 166also necessarily rotates. The rotational force of the fourth spur gear166 drives the drive gear 168 and causes the drive gear 168 and driveaxle 172 to rotate in a preselected direction from their initialposition. In alternative embodiments of the present disclosure, the gearassembly 130 may assume a plurality of different configurations in orderto transmit the rotary motion of the output shaft 138 of the motor 132.

Referring now to FIGS. 6-8, the rotation of the drive axle 172selectively displaces the first ball valve 120 within the ball valvereceptacle 222 of the fuel draw valve 102 to place the engine incommunication with the first and/or second fuel tanks. When receivedwithin the ball valve receptacle 222, the first ball valve 120 isdisposed between the first cam 287 and the second cam 285. The ballposts 292 of the first ball valve 120 engage the first cam surface 288and the second cam surface 289, as shown in FIG. 8.

Referring specifically to FIG. 8, the ball cap 304 is urged into one ofthree positions by rotating the first ball valve 120 within the ballvalve receptacle 222 such that the ball posts 292 translate along thefirst and second cam surfaces 288 and 289 and the ball cap 304 movesinto and out of engagement with the annular seals 236. During operationof the selector valve 100, the coil spring 306 continuously urges theball valve 120 away from the drive axle 172 as the drive axle 172 isrotated. As such, the ball posts 292 act as cam followers and guide theball valve 120 into and out of sealing engagement with the annular seals236. Moreover, to minimize distortion and wear of the first ball valve120, the ball cap 304 of the first ball valve 120 does not come intosubstantial contact with the interior surfaces of the ball valvereceptacle 222 when it is being rotated. Rather, the cam assembly isarranged such that the ball posts 292 travel along the first and secondcam surfaces 288 and 289 and prevent the ball cap 304 from contacting orrubbing against the interior surface of the ball valve receptacle 222.

Referring specifically to FIG. 7, the first ball valve 120 isselectively displaced into the first position by driving the drive axle172 in a counterclockwise direction such that the ball posts 292 travelalong the upper cam surfaces 296 of the first and second cams 287 and285 toward the first fuel tank draw port 108. As the ball posts 292approach the first lip 278 of the first and second cams 287 and 285, theball valve 120 is urged inwardly toward the drive axle 172, and the coilspring 306 compresses. As the ball valve 120 is urged inwardly, itcontinues to rotate without engaging the annular seal 236 of the firstfuel tank draw port 108. The ball valve 120 continues to travelcounterclockwise and is continually urged inwardly until the ball posts292 reach the edge of the first lip 278, after which the ball posts 292are displaced into the first pocket 290 by the force of the coil spring306. When the ball posts 292 are displaced into the first pocket 290,the first ball valve 120 is biased, or “positively dropped” into sealingengagement with the annular seal 236 of the first fuel tank draw port108. In other words, the ball cap 304 is dropped into engagement withthe annular seal 236 so as to close the opening in the annular seal 236.The ball cap 304 of the first ball valve 120 is dropped into engagementwithout having made substantial contact with the seal 236 prior thereto.As a result, wear and distortion of the first ball valve 120 and annularseal 236 of the first fuel tank draw port 108 is minimized.

When the first ball valve 120 is in sealing engagement with the annularseal 236, the ball posts 292 are displaced into the first pocket 290;however, the ball posts 292 are not in contact with the first and secondcam surfaces 288 and 289. Rather, the force of the coil spring 306 isused to urge the first ball valve 120 against the annular seal 236 ofthe first fuel tank draw port 108. In this first position, the ball cap304 abuts the opening in the annular seal 236 to “close” the first fueltank draw port 108. Moreover, the spring 306 maintains the positive sealbetween the ball valve 120 and the annular seal 236, allowingsubstantial control of fuel flow between the fuel selector valveassembly 100 and the first and second fuel tanks. This positive sealalso prevents any unwanted siphoning due to vehicle attitude.

To move the first ball valve 120 out of the first position, the driveaxle 172 rotates the ball valve 120 counterclockwise such that the ballcap 304 starts to move against the seal 236 of the first fuel tank drawport 108. After the ball valve 120 moves a certain distance on the seal236, the ball posts 292 engage the lower cam surface 297 and are urgedinwardly by the arcuate contour of the lower cam surface 297, therebyramping the first ball valve 120 off of the annular seal 236 as the ballvalve 120 is further rotated away from the seal 236. The drive axle 172continues to rotate the ball valve 120 counterclockwise such that theball posts 292 travel along the lower cam surface 297 away from thefirst pocket 290 until the first ball valve 120 has fallen off the seal236.

To move the first ball valve 120 into the second position, and thereby“close” the second fuel tank draw port 110, the drive axle 172 continuesto rotate the ball valve 120 counterclockwise until the ball posts 292similarly engage the second lip 280 and are displaced into the secondpocket 291, thereby dropping the first ball valve 120 into positivesealing engagement with the annular seal 236 of the second fuel tankdraw port 110. In the second position, the ball cap 304 abuts theopening in the annular seal 236 to “close” the second fuel tank drawport 110. To move the first ball valve 120 out of the second position,the drive axle 172 continues to rotate the ball valve 120counterclockwise to move the first ball valve 120 off the seal 236 ofthe second fuel tank draw port 110.

When it is desired to open both the first and second fuel tank drawports 108 and 110, the ball valve 120 is rotated until it is moved offthe seal 236 of either draw port 108, 110, or into a third position. Itshould be appreciated that the first and second cams 287 and 285 mayinclude any suitably contoured cam surfaces 288 and 289 to effectivelytranslate the ball valve 120 into at least first, second, and thirdpositions.

When the drive axle 172 is rotated by the gear assembly 130 to drive thefirst ball valve 120, the second ball valve 122 necessarily rotateswithin the ball valve receptacle 222 of the fuel return valve 104. Thus,the second ball valve 122 may be translated between a first position,wherein the ball cap 304 positively engages the annular seal 236 of thefirst fuel tank return port 114, a second position, wherein the ball cap304 positively engages the annular seal 236 of the second fuel tankreturn port 116, and a third position, wherein the ball cap 304 neitherengages the annular seal 236 of the first fuel tank return port 114 northe annular seal 236 of the second fuel tank return port 116.

When the first and second ball valves 120 and 122 are configured in thefirst position, the first fuel tank draw port 108 is sealed by the firstball valve 120 and the first fuel tank return port 114 is sealed by thesecond ball valve 122. As a result, the selector valve 100 draws fuelfrom the second fuel tank through the second fuel tank draw port 110 anddirects the fuel to the engine. Moreover, the selector valve 100 directsany fuel returned from the engine back to the second fuel tank throughthe second fuel tank return port 116.

When the selector valve 100 is configured in a second position, thesecond fuel tank draw port 110 is sealed by the first ball valve 120 andthe second fuel tank return port 116 is sealed by the second ball valve122. As a result, the selector valve 100 draws fuel from the first fueltank through the first fuel tank draw port 108 and directs the fuel tothe engine. Moreover, the selector valve 100 directs any fuel returnedfrom the engine back to the first fuel tank through the first fuel tankreturn port 114.

When the first ball valve 120 is configured in the third position,neither the first nor second fuel tank draw port 108, 110 are sealed bythe first ball valve 120. Therefore, the selector valve 100 draws fuelfrom both the first and second fuel tanks through the first and secondfuel tank draw ports 108 and 110 and directs the fuel to the engine.Moreover, with the second ball valve 122 in the third position, neitherthe first or second fuel tank return port 114, 116 are sealed by thesecond ball valve 122. Therefore, the selector valve 100 directs anyfuel returned from the engine back to the first and second fuel tanksthrough the first and second fuel tank return ports 114 and 116.

Referring back to FIG. 4, the motor 132 powers the rotation of the driveaxle 172 through the drive gear 168. As the drive gear 168 rotates, thedrive axle 172 displaces the first and second ball valves 120 and 122into one of multiple positions such that one of the protrusions 188 onthe drive gear 168 engages one of the switches 178 on the printedcircuit board 176. For instance, when the ball valves 120 and 122 aremoved into the first position, wherein the ball cap 304 positivelyengages the annular seal 236 of the first fuel tank return port 114, thedrive gear 168 is rotated such that a protrusion 188 engages a switch178. The switch 178 is thereby tripped, sending a signal to the motor132 to turn off.

While illustrative embodiments have been illustrated and described, itwill be appreciated that various changes can be made therein withoutdeparting from the spirit and scope of the present disclosure.

1. A selector valve having at least first and second ports, the selectorvalve comprising: (a) a closure element selectively displaceable betweena first position, wherein the closure element sealingly engages thefirst port, and a second position, wherein the closure element sealinglyengages the second port; and (b) a cam assembly configured to bias theclosure element into at least the first or second position in a mannersuch that the closure element does not come into substantial contactwith the first or second port when being moved into the first or secondposition.
 2. The selector valve of claim 1, wherein the closure elementis a ball valve.
 3. The selector valve of claim 1, wherein the camassembly comprises a first cam having a first cam surface and a secondcam having a second cam surface, wherein at least a portion of theclosure element engages and travels along the first and second camsurfaces to bias the closure element into at least the first or secondposition in a manner such that the closure element does not come intosubstantial contact with the first or second ports when being moved intothe first or second position.
 4. The selector valve of claim 1, whereinthe closure element is displaceable into a third position in which thefirst and second ports remain open.
 5. A selector valve having at leastfirst and second ports, the selector valve comprising: (a) a ball valveselectively displaceable between a first position, wherein the ballvalve sealingly engages the first port, and a second position, whereinthe ball valve sealingly engages the second port; and (b) a first camhaving a first cam surface and a second cam having a second cam surface,wherein at least a portion of the ball valve engages and travels alongthe first and second cam surfaces to bias the ball valve into at leastthe first or second position in a manner such that the ball valve doesnot come into substantial contact with the first or second port whenbeing moved into the first or second position.
 6. The selector valve ofclaim 5, wherein the ball valve is displaceable into a third position inwhich the first and second ports remain open.
 7. A method of selectivelyplacing a valve into communication with either a first or second port,the method comprising: (a) providing a closure element; (b) selectivelymoving the closure element between a first position, wherein the closureelement sealingly engages the first port, and a second position, whereinthe closure element sealingly engages the second port; and (c) biasingthe closure element into the first or second position in a manner suchthat the closure element does not come into substantial contact with thefirst or second port when being moved into the first or second position.8. The method of claim 7, wherein the closure element is a ball valve.9. The method of claim 7, further comprising moving the closure elementinto a third position, wherein the closure element is displaced betweenthe first and second positions.
 10. The method of claim 7, furthercomprising providing a cam assembly for biasing the closure element intothe first or second position in a manner such that the closure elementdoes not come into substantial contact with the first or second portwhen being moved into the first or second position.
 11. The method ofclaim 10, wherein the cam assembly includes a first cam having a firstcam surface and a second cam having a second cam surface, wherein atleast a portion of the closure element engages and travels along thefirst and second cam surfaces to bias the closure element into at leastthe first or second position in a manner such that the closure elementdoes not come into substantial contact with the first or second portwhen being moved into the first or second position
 12. A selector valvein communication with at least first and second ports, comprising: (a) aclosure element selectively displaceable between a first position,wherein the closure element sealingly engages the first port, and asecond position, wherein the closure element sealingly engages thesecond port; and (b) means for biasing the closure element into thefirst or second position in a manner such that the closure element doesnot come into substantial contact with the first or second port whenbeing moved into the first or second position.
 13. The selector valve ofclaim 12, wherein the means for biasing the closure element into thefirst or second position comprises a cam assembly.
 14. The selectorvalve of claim 13, wherein the cam assembly comprises a first cam havinga first cam surface and a second cam having a second cam surface,wherein at least a portion of the closure element engages and travelsalong the first and second cam surfaces to bias the closure element intothe first or second position in a manner such that the closure elementdoes not come into substantial contact with the first or second portwhen being moved into the first or second position.
 15. The selectorvalve of claim 12, wherein the closure element is a ball valve.